Pacific paradigms of environmentally-induced neurological disorders: clinical, epidemiological and molecular perspectives

Abstract

During the past quarter century biomedical scientists have begun to recognize the unique opportunities for studying disease etiology and mechanisms of pathogenesis in non-Western anthropological populations with focal, endemic diseases. Such natural experiments as they are called, are important paradigms for solving etiological and epidemiological problems of widespread medical significance, with an ultimate goal towards treatment and prevention. The systematic search for etiological factors and mechanisms of pathogenesis of neurodegenerative disorders is perhaps nowhere better exemplified than in the western Pacific. During the past three decades, the opportunistic and multidisciplinary study of hyperendemic foci of amyotrophic lateral sclerosis and parkinsonism-dementia which occur in different cultures, in different ecological zones and among genetically divergent populations have served as natural models that have had a major impact on our thinking and enhanced our understanding of these and other neurodegenerative disorders such as Alzheimer disease and the process of early neuronal aging. Our cross-disciplinary approach to these intriguing neurobiological problems and the accumulated epidemiological, genetic, cellular and molecular evidence strongly implicates environmental factors in their causation, specifically the role of aluminum and its interaction with calcium in neuronal degeneration. As a direct consequence of our studies in these Pacific populations, we have undertaken the long-term development of experimental models of neuronal degeneration, in an attempt to understand the cellular and molecular mechanisms by which these toxicants affect the central nervous system. Our experimental studies have resulted in the establishment of an aluminum-induced chronic myelopathy in rabbits and the development of neurofilamentous lesions after low-dose aluminum administration in cell culture. These studies clearly demonstrate the philosophy that chronic rather than acute experimental models of toxicity are necessary in order to enhance our understanding of human neurodegenerative disorders with long-latency and slow progression. Finally, the ultimate significance of these Pacific paradigms may well depend on our ability to comprehensively evaluate and synthesize the growing body of relevant scientific data from other human disorders and from widely divergent academic fields, as well as our ability to recognize emerging new models in nature.